Circuit for providing a delayed overriding control on one of a plurality of elevatorsafety devices



W. L. DUNCAN March; 26, 1963 3,082,845 CIRCUIT FOR PROVIDING A DELAYED ovERRIDING CONTROL oN ONE OF A PLURALITY OF ELEVATOR SAFETY DEVICES Filed Jan. 30. 1959 United States Patent O CIRCUIT FUR PROVIDTNG A DELAYED OVER- RIDING CNTROL ON ONE OF A FLURALITY F ELEVATR SAFETY DEVICES William L. Duncan, Dallas, Tex., assigner' to Montgomery Elevator Company, a corporation of illinois Filed Jan. 30, 1959, Ser. No. 790,154 2 Claims. (Cl. 137-52) This invention relates to an elevator control system and more particularly to a novel elevator safety circuit arrangement.

Automatic operatorless elevator systems often include certain safety devices or control circuitry which modifies or interrupts the operation of the elevator car or the doors thereof, in certain situations where such operation would be undesirable, as when a person is entering or leaving the car or when a person or object stands in the doorway. These safety devices sometimes include a photoelectric cell responsive to a beam of light projected across the door- Way of the car which operatesto modify the overall control circuits of the system to delay the closing of the elevator doors and departure of the car from the iioor when the light beam is broken. In some installations, a pair of light beams and photocells are used with the light beams spaced vertically in the doorway. A passenger or person in the hallway may interrupt one of the light beams to hold the car for another passenger who is coming or merely to see what will happen. If a car is delayed for an excessive period of time, it impairs the efficiency of the overall operation of :the automatic system and is particularly undesirable if there is no beneficial result gained from the delay. Furthermore, the photocell or light source lsometimes wear out or become inoperative in use and, at least where a multiple light control system is employed, it is generally unnecessary that the car be taken out of operation until it can be repaired, although this is the necessary result of such an occurrence with present systems.

lt is a principal object of the present invention to provide a control system in which excessive delay is prevented upon actuation of only one of a plurality of safety devices, and further to permit operation of a car when one of a plurality of safety devices is rendered inoperative.

One feature of the invention is the provision in a control system of control means for controlling the operation of the elevator car in a predetermined sequence of operations, a plurality of sensing means each responsive to a condition which renders ioperation of the car undesirable, and means responsive to actuation of only one of a sensing means for temporarily modifying operation of the control means, such means being responsive toactuation of a plurality of the sensing means for modifying the operation until this actuation is terminated. Another feature is that the actuation of one sensing means modifies the operation ofi-the control mean-s and initiates operation `of the time delay means which returns the control means to its original operating condition unless another sensing means is actuated.

A further feature is that the system includes an enabling circuit having an operative and an inoperative condition, normally maintained in its operative condition, together with first circuit means responsive to one sensing means for rendering the enabling circuit means inoperative, second circuit means responsive to actuation of the first circuit means and a further operating condition of the circuit for rendering the enabling circuit operative, and further circuit means responsive to the rst circuit means and the enabling circuit in its operative condition for modifying the operation of the control means.

Still another feature of the invention is that the enabling circuit includes the operating coil of a relay and time ice delay means comprising a capacitor connected in parallel with the relay coil for maintaining it energized for a period following the interruption of Ilthe energizing circuit thereof.

lFurther Afeatures and advantages will readily be apparent from the following specification and from the drawings, in which:

FIGURE l is a diagrammatic elevation of an elevator car illustrating an embodiment of the invention;

FIGURE 2 is a simplified diagram of the electrical control system yfor an elevator, embodying the invention; and

FIGURE 3 is a key for the circuit of FIGURE 2.

Automatic safety devices are essential in automatic operatorless passenger elevators. However, it is desirable that the safeties be incorporated in the control circuit in a manner preventing misuse or unnecessary interruption of system operation in the event of a failure of the safety device. The specific embodiment of a photoelectric cell safety control system to be described below satisfies these requirements of providing the necessary operational safety feature without inducing misuse or rendering a car inoperative upon failure thereof.

ln FlGURE 1, an elevator car 10 is shown at a landing 11 with its doors 12 open. A pair of photoelectric cell safety -devices are mounted in the doorway of the car including light sources or lamps 13 and 14 and photocell or pickup units 13a. and 14a. In practice, the beam `of the upper assembly 13, 13a is usually about thirty inches from the floor of 4the car While the -beam of the Ilower assembly 114, 14a is about eighteen inches above the floor. Thus, either the arm or the lleg of a person entering or leaving the car will break one of the light beams as the person approaches the car doorway, and through the circuit to be idescribed below, delays the operation of the car to permit such person to enter or leave.

Turning now to FTGURES 2 and 3, the basic and simplified operation of a portion of the elevator control system will be described. The circuits shown here include only those elements which are directly concerned with the novel safety system disclosed and if further information is desired regarding a more complete control system, reference may be made to Pierson et al. application, Serial No. 596,295, filed July 6, 1956, now Patent No. 2,867,291, or Beck and Holuba application, Serial No. 669,678, liled July 2, 1957, now Patent No. 2,880,- 821.

The circuit is energized by connecting leads 15 and d6 to a suitable power source as volts A C. Briefly, when the car is running through the shaft, the door open relay DOR is not energized, as each of the various energizing circuits associatedwith it are open. Furthermore, contact SBR in the circuit of TSR relay, associated with the shunt break relay (not shown) is open. As the car approaches a floor at which a stop is to be made, and is leveled with the floor, contact LR-1 associated with the levelingY control circuitry (not shown) closes, completing a circuit through normally closed contact TSRl, energizing relay DOR and contact LR-Z opens and remains open until contact TS has also opened. Thus, at

.no time while the car is coming into the floor and the f doors are opening is relay TSR energized. Contact DORI closes completing a holding circuit for relay DOR,

which in turn actuates the power kdoor-opening mechanism (not shown).

Normally open contact DORZ closes completing an energizing circuit for stop timer TS, through contact OL, an open limit switch which is actuated by the doors when they reach their full open position. When TS timer is energized, contact TS in the circuit of stop timer relay TSR opens and remains open for a predetermined time kwhen the circuit is broken.

aoeasee interval after the circuit of the timer has been broken, which of course occurs when the doors reach their full open position.

After timer TS has run its cycle, contact TS closes energizing relay TSR and opening contact TSRI in the circuit of door relay DOR, deenergizing the relay. It should be noted that contact TSR-2 closes at this time. The power door mechanism is actuated closing the doors whereupon the car is conditionedfor further travel.

Turning now to the photocell systems, lamps -13 and 14 are energized through step-down transformers connected across the line. Photocell unit 13a includes a normally open contact 13b which is closed, by suitable circuitry (not shown) when the light beam from lamp 13 is broken, energizing relay PC(1). Similarly, photocell unit 14a includes normally open contact 1417 which closes when the light beam from lamp 14 is broken, energizing relay PCX2).

An enabling relay EBD is energized through two parallel circuits, one including series connected normally closed contacts PC(l)-2 and PC(.2)2 and the other including series connected, normally open contacts PC(1)-3 and PC('2)-3. Thus, relay EBD is normally energized and its associated contact EED is closed. Assuming that both light beams are broken, as would happen when a passenger enters or leaves the car, both photocell sensing units are actuated and contacts 13b and liib close. This energizes relay PCG) and PCCZ) closing contacts PC(1)-3` and PC(Z)-3, and relay BED remains energized. At the same time, contacts PC(i)-l and IC(2)1 close, completing a circuit through Contact EBD energizing relay PCM, the master photocell relay.

There, are two normally open contacts associated with the PCM relay, both of which close when it is energized. Contact PCMl is connected in parallel with contact TSR in the circuit of door relay DOR and has no effect unless TSRl is open '(when the doors start to close). When PCMI closes, the circuit for DOR relay is completed through contact TSRZ reopening the doors. Contact PCMZ closes in the circuit of stop timer TS and remains closed until the interruption of the light beams is terminated whereupon the circuit for timer TS opens and, after the brief timing cycle the doors reclose, as outlined above.

A time delay circuit is associated with relay EBD to provide for a temporary functioning of the safety circuit where only one light beam is broken. Relay BED is a direct current relay and is energized from the alternating current supply line through a rectifier 17 and current limiting resistor 18. Connected in parallel with the resister and relay coil combination is a capacitor 19 which charges when the energizing circuit for relay EBD is completed and which discharges through resistor 18 and the relay coil keeping it energized for a few seconds, This time delay is sufficient to keep contact BBD closed while contact PC`(1)1 or EC(2)-2` closes, energizing relay PCM momentarily. Momcntary energization of relay PCM closes contacts PCMl and PCMZl as outlined above and recycles the stop timer TS, reopening the doors and holding them open for the usual period. If in the meantime the second photocell unit is energized, the cnergization circuit or relay BED is completed and relay PCM remains energized holding the door open until the barrier is removed. However, if a passenger has merely broken one of the beams, asin an eort to vdelay the operation of the car unnecessarily, the doors merely reopen and then reclose, even though the one beam is still broken. In most cases the closing action of the door will be enough toV cause the person obstructing the light beam to remove the obstruction from the door. if, however, this should not be done, contact SEC associated with the sensitive edge on the door is closed when the door engages the interfering object. This reenergizes relay DOR causing the doors to reopen and preventing damage or injury.

If one of the photocell units should become inoperative, as when a lamp burns out, its associated contact, as 13b or 14b, closes, and the relay, PC(1) or PCQZ), is energized. The photocell safety system continues to function when the remaining light beam is broken as this single operation actuates both relays BBD and PCM, andV the system operates as if there were but a single photocell control over relay PCM.

When one of the photocell units is rendered inoperative, as by the failure of a lamp, it is desirable that this information be communicated to a central point, as a master control panel. Accordingly, contacts PC(1)4 and PC(2)4 are provided, connected in parallel in the energization circuit of photocell indicator relay PCI, which is preferably a time delay relay. When one of the two contacts closes the cycle of relay PCI is initiated and, after a suitable period, as two minutes or so contacts PCI close completing a circuit energizing an indicator lamp 2t). The failure will thus be apparent to the operator or supervisory personnel who inspect the system periodically and the necessary repairs may be effected.

The foregoing detailed description is given for clearncss of understanding only and no unnecessary limitations are to be understood therefrom, as some modifications will be obvious to those skilled in the art.

I claim:

1. In an elevator system which includes means for controlling movement of the car, a safety circuit comprising: a pair of spaced sensing means each responsive to a condition which renders operation of the car undesirable; an enabling circuit, including the energizingcoil of a relay, having an operative and an inoperative con dition; parallel energizing circuits for said relay coil each including series connected switch contacts associated with each of said sensing means, said enabling circuit being completed, energizing the relay `when both of said sensing means are in the same condition, said circuit being open when said sensing means are in opposite conditions; time delay means for maintaining the coil of said relay temporarily energized upon interruption of one of said parallel circuits; and circuit means for modifying the operation of said control means, permitting operation of said elevator car in response to a condition which renders operation of the car undesirable, including contacts Refer-ences Cited inthe file of this patent UNiTBD STATES PATENTS 1,822,152 Kinnard et al. Sept. 8, 1931` 2,601,250 Bruns et al. June 24, 1952 2,634,828 Bruns et al. Apr. 1'4, 1953 2,785,772 Santini Mar. 19, 1957 2,806,553 Eames Sept. 17, 1957 2,900,521 Eames Aug. 18I 1959 

1. IN AN ELEVATOR SYSTEM WHICH INCLUDES MEANS FOR CONTROLLING MOVEMENT OF THE CAR, A SAFETY CIRCUIT COMPRISING: A PAIR OF SPACED SENSING MEANS EACH RESPONSIVE TO A CONDITION WHICH RENDERS OPERATION OF THE CAR UNDESIRABLE; AN ENABLING CIRCUIT, INCLUDING THE ENERGIZING COIL OF A RELAY, HAVING AN OPERATIVE AND AN INOPERATIVE CONDITION; PARALLEL ENERGIZING CIRCUITS FOR SAID RELAY COIL EACH INCLUDING SERIES CONNECTED SWITCH CONTACTS ASSOCIATED WITH EACH OF SAID SENSING MEANS, SAID ENABLING CIRCUIT BEING COMPLETED, ENERGIZING THE RELAY WHEN BOTH OF SAID SENSING MEANS ARE IN THE SAME CONDITION, SAID CIRCUIT BEING OPEN WHEN SAID SENSING MEANS ARE IN OPPOSITE CONDITIONS; TIME DELAY MEANS FOR MAINTAINING THE COIL OF SAID RELAY TEMPORARILY ENERGIZED UPON INTERRUPTION OF ONE OF SAID PARALLEL CIRCUITS; AND CIRCUIT MEANS FOR MODIFYING THE OPERATION OF SAID CONTROL MEANS, PERMITTING OPERATION OF SAID ELEVATOR CAR IN RESPONSE TO A CONDITION WHICH RENDERS OPERATION OF THE CAR UNDESIRABLE, INCLUDING CONTACTS 